Axial flux permanent magnet motors generally have high torque density (torque rating per unit volume) and can be advantageous for low speed, high torque applications, including direct drive. However, controlling motors at low speed can prove more difficult than at higher speeds because more time passes between position feedback signals. This usually means that high resolution position feedback is desirable to facilitate control.
Normally, this is done with a separate optical encoder or similar device. An optical encoder, as a separate device later installed on the motor, comes with its own mechanical constraints which may impose new design constraints on the overall motor/optical encoder assembly. Additional consideration must be taken for proper alignment.
Accordingly, there is a particular need for an improved axial flux motor which overcomes the problems recited above.